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What does a shark see? You may be surprised

A team of scientists has created an amazing new "shark vision" camera that reveals how the world appears to these deep sea predators.

What does the world look like through a shark’s eyes? Scientists weren’t sure, so a team of researchers from the American Museum of Natural History set out to investigate. According to a report from Phys.org, scientists have found that catsharks, a species known to exhibit bioflourescent characteristics, can see their own patterns with improved clarity the deeper they travel.

According to co-author John Sparks, a curator at the American Museum of Natural History’s Department of Ichthyology, “We’ve already shown that catsharks are brightly fluorescent, and this work takes that research a step further, making the case that bioflourescence makes them easier to see by members of the same species. This is one of the first papers on bioflourescence to show a connection between visual capability and fluorescence emission, and a big step toward a functional explanation for fluorescence in fishes.”

Bioflourescence refers to the process by which organisms absorb light and then re-emit it as a different color. There are more than 180 known species of fish that glow in the dark, exhibiting a wide array of colors and patterns.

Unlike mammals, fish primarily see the world in blue – which makes sense, because they live in the water. Research has shown that as fish go deeper and blue light becomes scarcer, certain species can absorb the remaining blue light and recast it as brilliant neon green, red or orange hues.

Scientists wanted to find out how bioflourescence impacts the daily life of animals that utilize it, so they employed a technique called microspectrophotometry to study how sharks’ eyes absorbed light. Researchers found that the catsharks had long rod pigments that helped them see in the low-light environment of the deep ocean, and recreated a camera that simulated the shark’s field of view.

On a series of dives late at night, researchers put the camera to the test by filming lights intended to mimic the sharks’ bioflourescence in about 100 feet of water. While the light was invisible to the human eye, the specially designed camera revealed that sharks have a much different picture of the ocean than a person would.

According to lead author David Gruber, “Some sharks’ eyes are 100 times better than ours in low-light conditions. They swim many meters below the surface, in areas that are incredibly difficult for a human to see anything. But that’s where they’ve been living for 400 million years, so their eyes have adapted well to that dim, pure-blue environment.”